In recent years, various kinds of electronic devices including a mobile phone and a personal computer are progressively having a high performance and being miniaturized. With this trend, an input device for operating these electronic devices is required to have a good operational feeling and a reliable operability. A conventional type of this kind input device is explained using FIGS. 7 and 8. FIGS. 7 and 8 are cross sectional views of the conventional input device, and FIG. 8 shows a status the input device being press-operated. The input device has ball 1 made of insulating resin, upper case 3, lower case 4, frame 5, and wiring board 6.
A plurality of magnets 2 which is made of ferrite or the like and formed in substantially a disk shape is embedded in an outer periphery of ball 1 with a certain space therebetween. Upper case 3, lower case 4, and frame 5 are made of a thin metal plate. Upper case 3 and lower case 4 are attached to frame 5 movably in up and down directions. Within upper case 3 and lower case 4, ball 1 is rotatably accommodated, and an upper part of ball 1 is protruded from an opening in an upper side of case 3.
A plurality of wiring patterns (not shown) are formed on upper and lower sides of wiring board 6, and a plurality of magnetic detecting elements 7 such as a hall element are mounted on the upper side of wiring board 6. A lower end of frame 5 is fixed to wiring board 6. Magnetic detecting elements 7 are placed facing ball 1 with a certain gap.
On the upper side of wiring board 6, push switch 8 (hereinafter, switch) is mounted. Switch 8 is placed under ball 1. Switch 8 has push button 8A protruded upward. An upper face of push button 8A is in contact with a bottom face of lower case 4.
Thus constituted input device is installed in an operational part of electronic devices (not illustrated) such as a mobile phone and a personal computer. When installed, the upper part of ball 1 is protruded from the operational part. Magnetic detecting elements 7 and switch 8 are electrically connected to an electronic circuit (not illustrated) of the device through the wiring patterns or the like.
In above constitution, a plurality of menus including a name and a song title, and a cursor or the like (not illustrated) are displayed on a display (not illustrated) of the device which is composed of such as liquid crystal display or the like. In this status, a user turns an upper part of ball 1 with a finger, then magnet 2 embedded in the periphery of ball 1 moves with it. If ball 1 is turned in a right direction, magnet 2A first comes close to magnetic detecting element 7, and then magnet 2B comes close to magnetic detecting element 7.
Magnetic detecting element 7 detects magnetism of the plurality of magnets 2 alternately coming close and leaving out, and outputs a certain pulse signal to the electronic circuit of the device. With this pulse signal, the electronic circuit of the device finds out a rotational direction and a rotational angle of ball 1, and then moves the cursor or the like on the menus displayed in the display of the device toward the right direction.
When the user turns ball 1 to a left, front, back, or intermediate diagonal direction, a pulse signal is likewise output from one or more of magnetic detecting elements 7. The electronic circuit then detects the rotational direction and the rotational angle of ball 1, and moves the cursor or the like in the left, front, back, or diagonal direction.
When the user presses the upper part of ball 1 while the cursor or the like is stayed on a desired menu, upper case 3 and lower case 4 accommodating ball 1 moves downward as shown in FIG. 8. As a result, the bottom face of lower case 4 pushes button 8A, thus electrically conducting switch 8. The electronic circuit detects the electrical conduct, fixing the menu or displaying a following menu.
Namely, a user turns ball 1 in a certain direction while watching a display of the device, then the cursor or the like displayed on the display is moved toward the direction. Thus the user may select the menu. The user may fix the menu or display a following menu by press-operating ball 11. This kind of input device is disclosed in Patent Document 1, for instance.
However, with this conventional input device, if the user mistakenly presses ball 1 while turning ball 1, ball 1 moves down with upper case 3 and lower case 4, changing the gap between ball 1 and magnetic detecting element 7. Because of it, the pulse signals output from magnetic detecting element 7 are varied, causing an error in detecting the rotational direction and the rotational angle.
Patent Document 1: Japanese Patent Unexamined Publication No. 2004-5091